Hi everyone,

--If you are just looking for quick reference damper tuning tips: skip to the end, where I will summarize the generalizations--

This will be fairly dense, so grab some popcorn and buckle up.

Anyone can grasp these concepts, I believe in you.

We will be starting with the basics. I would like to begin with a quote: "We need shock absorbers- even if they do not absorb shocks, which they do not. Springs absorb shocks by compressing in response to vertical accelerations. Shock absorbers dampen the energy which is stored in the springs" (Smith, Pg. 74) (Shock absorbers will now be referred to as dampers)



With this in mind, I want to answer three key questions to keep in mind when setting up the damping of your car:

-A- A damper does just what it says on tin: It dampens suspension movement!

A damper simply slows down or "holds" the movement of a spring. If a car's suspension moved without any damping it would naturally bounce up and down like a pogo stick. If "this oscillation were not dampened... this would do terrible things to the tire's compliance with the road" (Smith, Pg. 74)

-A- We can use the damper to "hold" the suspension in desirable locations!

If we think of ride height as being controlled by the spring itself, we can also equate the slowing down of the movement of the spring to "holding" the ride height in various positions. This characteristic allows us to create handling altering effects.



This is achieved by slowing down either the compression of the spring (bump) or the expansion of the spring (rebound). Since springs naturally bounce up and down in a cycle, if we were to "slow down" the spring each time it compressed during the cycle (with higher bump damping) we would also "hold" the ride height in a higher position, while oppositely, "slowing down" the spring's expansion during the cycle (higher rebound damping) "holds" the ride height in a lower position.

For illustrative purposes TRY this extreme experiment:

We will drastically effect the handling of any car by doing the following: "Hold" the front suspension down (set minimum bump damping and set maximum rebound damping), then "hold" rear suspension up (maximum bump damping and minimum rebound damping). This makes the car extremely unstable.

Next, "hold" the rear suspension down (apply minimum bump damping and maximum rebound damping), then "hold" the front suspension up (maximum bump damping and minimum rebound damping). This conversely makes the car an understeery mess.

Now, TRY this experiment:

"Hold" both ends of the car very low to the ground (set both front and rear bump to minimum and both front and rear rebound at maximum) this causes extreme oversteer on corner entry, and extreme understeer on corner exit. Then, "hold" both ends of the car very high (both front and rear bump high with front and rear rebound very low) This, again, oppositely causes extreme understeer on corner entry, and extreme oversteer on corner exit.

These experiments establish the effects of the four adjustable elements of damping within Forza Motorsport.

Congratulations, you have unlocked very useful foundational tuning knowledge!

-A- We can adjust these characteristics to produce desirable handling effects!

To start, let me state a tuning rule to live by:

!!!ALWAYS make adjustments to the end of the car that is suffering the loss of grip!!!

I.E. If the rear of the car is unstable, fix the rear of the car. If the front is unstable, fix the front of the car. This is good practice and should be maintained at all costs.

To preface; "we need more damping force in rebound, than we do in bump. This is simply because the bump stroke damps the movement of the unsprung mass (wheel and tire) which is, by definition, much less than that of the sprung mass (body and chassis) and, in addition, DOESN'T VARY MUCH due to dynamic load conditions. The rebound stroke, on the other hand, damps the reaction of the sprung mass (body and chassis)." (Smith, Pg. 76)

This above paragraph highlights three essential things to keep in mind:

1- Your bump damping is ALWAYS necessarily going to be less than your rebound damping.

2- Your bump damping, once set correctly, will essentially stay ALMOST THE SAME across ALL corners, and ALL conditions.

3-Your rebound damping is going to play the primary role in the handling of your vehicle, since it is by definition doing more work than the bump damping.

Now, let's get started.

The bump damping of your car is essential in two ways, and should be set in the following order:

Start- (Front and Rear) Begin with a high value (7/8 of max), since "all racing cars are overdamped by conventional comfort standards." (Smith, Pg. 76). We will slowly work down, first in increments of 1.0, to find our setup window, then, in small adjustments of 0.1-0.2 to dial it in.

1- (Front) Corner entry. Decreasing front bump damping will allow weight to transfer to the front wheels more quickly. This increases front grip up until the point where the damping becomes too soft, and it begins to change directions in a sluggish or unpredictable manner.


(Smith, Pg. 33)

2- (Rear) Corner exit. Decreasing rear bump stiffness will allow weight to transfer to the rear wheels more quickly. Again, increasing rear grip up until the point where the rear becomes sloppy, and the car hangs out its rear refusing to "take its set".


(Smith, Pg. 33)

Rebound damping will provide immense feedback through the steering wheel, and should be looked at as the way to control reaction to changes in steering input.

It is essential in four ways, and should be adjusted in the following order:

Start- (Front and Rear) Begin with a value near maximum since "Too little rebound adjustment results in a floating or oscillating car." (Smith, Pg 77) Again, decreasing in values of 1.0, followed by values of 0.1-0.2 to dial in.

1- (Front) Corner Exit. Decreasing front rebound will allow the front suspension to expand away from the car more quickly, when weight is transferred to the rear, increasing tire contact and front grip.

2- (Front) Mid Corner. Next, increasing front rebound will have the effect of increasing grip during the side-to-side weight transfer across the front axle. Balance this characteristic by repeating steps 1 and 2 until grip is satisfactory in both conditions


(Smith, Pg. 37)

The above diagram depicts a turn to the right at 1.4g, with the chassis rolling to the left.


(Smith Pg. 37)

The above diagram depicts an identical 1.4g turn to the right, but crucially, with reduced ride height of 1".

Since we understand that sprung mass (chassis and body) movement is controlled by rebound damping, and we also understand that higher rebound values mean we "hold" the suspension at a lower ride height, we can utilize rebound damping in the mid corner to achieve slightly higher loading of the tires.

3- (Rear) Corner Entry. Decreasing rear rebound will allow the rear suspension to expand away from the car, when weight transfers to the front wheels under braking, increasing tire contact and rear grip.

4- (Rear) Mid Corner. Increasing rear rebound will have the same effect of Step 2 of sharpening side-to-side feeling of weight transfer on the rear wheels, until it becomes too firm. Again, find the balance by repeating steps 3 and 4.

Finally, when getting ready to race; "Different tracks will require different (damper) adjustments. The ratio of bump to rebound usually stays pretty much the same as does the ratio of front to rear damping, but the total amount of damping required changes with the nature of the track" (Smith Pg. 76)

This is where personal preference is essential.

Change all four settings EQUALLY at each track to compensate for bumps/curbs. Generally you will want to use lower settings for bumpy tracks, and higher for smooth tracks.

Some drivers choose to keep low settings no matter the track, so they can try different lines across curbs. Others prefer higher settings to maintain consistency, and to compensate for changes in fuel load.

And that's it! You're ready to race

I would like to add a misconception I commonly see by starting with this quote:

"(Dampers) have no effect on the amount of load that will be transferred in either plane, due to a given acceleration or on the amount of roll that will be generated by a given cornering force. They do, however, affect that rate at which load is transferred due to spring compression and the time that it takes a given load transfer to effect a change in wheel camber." (Smith, Pg. 76)

A quote from the in-game rebound tuning advice:

"Drivers can also use rebound damping to aid in straight line grip. For example, lowering rear rebound damping speed will transfer weight to the front wheels during braking"

In my opinion this slightly misleading, in that it is implied that decreasing rebound damping will transfer more weight to one end of the car or the other. In reality, since the wheels are free to leave the ground, front/rear weight transfer is unaffected by rebound damping.

E.G. if we were to raise the rear of the car up with a jack placed on the chassis, the rear rebound setting of the dampers wouldn't make the car harder to lift up. It would only affect how quickly the rear wheels drop down.

(Problem- Solution)

CORNER ENTRY: Oversteer- Decrease Rear Rebound
Understeer- Decrease Front Bump

MID CORNER: Oversteer- Increase Rear Rebound
Understeer- Increase Front Rebound

CORNER EXIT: Oversteer- Decrease Rear Bump
Understeer- Decrease Front Rebound

ACADMEIC SOURCE: Carroll Smith, "Tune to Win", 329 West Aviation Rd Fellbrook CA 92028, Aero Publishers Inc, 1974



Thank you very much for reading through! Please feel free to leave any comments, advice, or critiques below.